Motor controller



p 0.- 9 P. a. HARWOOD E! m. 2,214,020

I MOTOR CONTROLLER File V- 18, 1939 2 Sheets-Sheet 1 Sepi. w, 1 4 P. s.HARWOOD El AL MOTOR CONTROLLER 2 Sheets-Sheet 2 Filed Nov. 18, 1939 3/a). MMM

Patented Sept. 10, 1940 UNITED STATES PATENT OFFICE MOTOR CONTROLLER ofDelaware Application November 18, 1939, Serial No. 305,098

9 Claims.

This invention relates to motor control systems, and while not limitedthereto is particularly applicable to systems of control for motordriven. machine tools such "as wire drawing machines of the multipleunit type.

Wire drawing machines of the multiple unit type are usually providedwith a plurality of reducing dies each of which has a pulling drumassociated therewith. The several drums are driven by a single motor andthe wire is wrapped around said drums for successive drawing through thereducing dies.

In preparing such machines for a drawing operation the operator threadsthe wire through the first reducing die and then operates the motor fora short period to effect winding of a' few turns of the wire upon thefirst pulling drum. The wire is then threaded through the secondreducing die and the motor is again operated for a short period toeffect winding of a few turns of the wire upon the second pulling drum.This process is repeated until the wire is successively threaded throughall of the reducing dies and wound upon their associated pulling drums.During these operations it is necessary to operate the motor at arelatively low speed, and in practice it has been found that a period ofapproximately 4 seconds must be allowed for each of the windingoperations.

It has heretofore been proposed to control wire drawing machines of themultiple unit type by means of a time limit controller including aplurality of accelerating switches which operate to shunt a startingresistance for the driving motor in steps separated by given timeintervals. However, such controllers have been found objectionable forthe following reason. During preparation of the machine for a drawingoperation the .load on the driving motor is increased each time the wireis threaded through a die and wound upon the pulling drum associatedtherewith. The accelerating switches of a controller of the aforesaidtype may be set to operate successively at 4 seconds intervals so thatregardless of vary ing load conditions the motor will operate at arelatively low speed for the required interval during each of thewinding operations. However, when the wire is to be wound upon thesecond drum or'possibly the third drum the driving motor may not havesufficient torque to start until after the first accelerating contactorcloses.

It is, therefore, necessary for the operator to wait at least 4 secondsbefore the winding operation is started, and if suificient torque is notdeveloped for starting until the second accelerating contactor closes itis necessary to wait 8 seconds. Obviously such periods of delay beforethe motor is started are undesirable, and the present invention hasamong its objects to provide an improved controller which overcomes thisobjection.

Another object is to provide an accelerating controller for motor drivenmachines of the aforesaid type which operates at an extremely rapidaccelerating rate until the motor starts and thereafter operates at areduced accelerating rate to bring the motor up torunning speed.

Various other objects and advantages of the invention will hereinafterappear.

The accompanying drawings illustrate an embodiment of the inventionwhich will now be described, it being understood thatvariousmodifications may be made in the embodiment illustrated withoutdeparting from the spirit and scope of the appended claims.

In the drawings,

Figure 1 is a straight line diagrammatic representation of a controlsystem embodying the invention, and

Fig. 2 is a key illustration of the switches and relays embodied in Fig.1.

The illustration of the switches and relays in Fig. 2 shows them withtheir coils and contact members disposed in horizontal alignment withtheir positions in the straight line circuits of Fig. 1 s6 that thereader may readily determine the position of the coil and contactmembers of any switch or relay in the straight line circuit. Thereference characters also serve as a guide to the relation between the,operating coils of the switches and relays and their associatedcontacts. For example in switch IM the operating coil IM operatescontacts [M IM and IM The switches and relays are named as follows:

IM M IA 2A 3A 4A 5A IVR 2VR 3VR AS Armature shunt switch DB Dynamicbraking switch FA Field accelerating switch CT Timing relay UVUndervoltage relay Referring to Fig. 1, the same illustrates a direct}Main switches Accelerating switches Voltage relays current motor M tobe supplied with current from a direct current supply circuit indicatedby lines L L The motor shown is provided with an armature A, a seriesfield winding F and a shunt field winding F The control means for motorM includes a pair of electromagnetically operated main switches IM and2M for connecting armature A, and series field winding F across lines LL in series with a plurality of starting resistance sections R to Rinclusive. The control means for said motor also includes a plurality ofelectromagnetically operated accelerating switches IA to 5A forsuccessively shunting resistance sections R to R a field acceleratingswitch FA for controlling accelerating resistance sections R and 1'1. inthe shunt. field circuit of said motor, and a dynamic braking switch DBfor connecting a dynamic braking resistance R in shunt with armature A.I The main switches IM and 2M and also the accelerating switches IA to5A; inclusive, are of a conventional type, said main switches eachhaving an operating winding M and said accelerating switches each havingan operating winding A and a holding winding A The operating windings ofmain switches IM and 2M and also the operating windings of acceleratingswitches 'IA to 5Aare controlled by a master switch MS having stationarycontacts I, 2, 3 and 4 and cooperating movable contacts l 2, 3 and 4Response of the accelerating switches IA, 2A, and 3A is timed bycapacitors C C and C respectively, and also by voltage relays IVR, 2VRand 3VR, respectively. Capacitor C and a resistance r are connected inparallel with the holding coil IA of accelerating switch IA; capacitor Cand a resistance r are connected in parallel with the holding coil 2A ofaccelerating switch 2A, and capacitor C and a resistance r are connectedin parallel with the holding coil 3A of accelerating switch 3A. Voltagerelay IVR is provided with a set of normally closed contacts IVR. forconnecting a resistance 1 in shunt with the holding coil IA? ofaccelerating switch IA; voltage relay ZVR is provided with a setofnormally closed contacts ZVZR, for connecting a resistance r in parallelwith the holding coil-2A of accelerating switch 2A, and voltage relay3VR is provided with normally closed contacts 3VR for connecting aresistance r in parallel with the holding coil 3A of accelerating switch3A. The operating windings IVR 2VR and 3VR of said voltage relays areconnected in parallel with each other and with a resistance section Rand the armature shunt switch AS provides for connection of said windingand said resistance across the terminals of armature A.

Accelerating switches 4A and 5A are rendered operative upon response ofthe dynamic braking switch DB. Relay CT controls the dynamic brakingswitch DB and the armature shunt switch AS and said relay is providedwith timing control means including a capacitor C which is connectedacross the terminals of operating winding GT through the medium of aresistance r". Field accelerating switch FA is controlled byaccelerating switch 5A and operation thereof is timed by a capacitor Cwhich is connected across the terminals of operating winding FA throughthe medium of a resistance T The controller also includes stop pushbuttons 5 and 6 which are connected in series in the energizing circuitof undervoltage relay UV and as hereinafter set forth said relay whendeenergized necessitates return of master switch MS to I The operationof the aforedescribed controller and the circuit connections thereofwill now be more fully described.

With voltage on lines L L and master switch MS in ofi position, undervoltage relay UV is energized by a circuit extending from line L throughcontacts I, I 2 and 2 of master switch MS through the operating windingUV of said relay and through stop push buttons 5 and 6 to line 1?. Uponresponse of the under voltage relay UV the contacts UV thereof shuntmaster switch MS to. establish a maintaining circuit for the operatingwinding UV of said relay.

Also with voltage on lines L L the holding windings associated withaccelerating switches IA to 5A and the operating windings associatedwith field accelerating switch FA and timing relay CT are energized asfollows. Holding winding IA of accelerating switch IA is energizedthrough the medium of contacts IM of main switch IM and the capacitor Cassociated therewith is charged through the medium of resistance 1'Holding winding 2A of accelerating switch 2A is energized through themedium of contacts IA of accelerating switch IA and the of resistance 1Holding windings 4A and 5A of accelerating switches 4A and 5A areconnected in series and are energized through the medium of a resistance1 Operating winding FA of field accelerating switch FA is energizedthrough the medium of contacts 5A of accelerating switch 5A and thecapacitor C associated therewith is charged through the medium ofresistance 1 Operating winding CT of timing relay CT is energizedthrough the medium of contacts 3A of accelerating switch 3A and thecapacitor C as,- sociated therewith is charged through the medium ofresistance 1'".

Upon energization of field accelerating switch FA contacts FA and FAclose, and upon closure capacitor C associated therewith is charged ofcontacts FA resistance sections R" and R are shunted to provide forconnection of shunt field switch AS and the contacts CT thereof open toprevent energization of the dynamic braking switch DB.

To effect starting of the motor, master switch MS is moved into its onposition. The operating windings IM and 2M of main switches IM and 2Mare then energized by a circuit extending from line L through contactsUW of under voltage relay U.V through contacts 2, 2 3 and 3 of saidmaster switch, through the operating windings of said main switches andthrough contacts UV of said under voltage relay to line L. Upon responseof main switches 'IM and 2M armature A and series field windings F areconnected across lines L L through the medium of resistance sections Rto R inclusive. Also the shunt field winding F is connected directlyacross lines L L by contacts FA of field accelerating switch FA andresistance section R is connected across the contacts DB immediatelyupon response of main switches IM andZM the operating windings IA 2A and3A of accelerating switches IA, 2A and 3A are energized by a circuitextending from line L through contacts UV of under voltage relay UVthrough contacts 2, 2 4 and i of the master switch MS to and throughsaid operating windings and through contacts IM and iM of said mainswitches to line L However, accelerating switches IA, 2A and 3A do notrespond immediately due to the action of their associated holdingwindings A 'Also upon response of main switches IM and 2M the operatingwinding AS of armature shunt switch AS is connectedacross lines L Lthrough the medium of contacts IM and 2M of said main switches. Thearmature shunt switch AS thus responds immediately upon closure of mainswitches IM and 2M and the contacts AS thereof connect resistance r andthe operating windings IVR 2VR and SVR of the voltage relays across theterminals of armature A to render said voltage relays responsive togiven counter-voltage values in the motor circuit.-

Upon response of main switch IM the contacts lM thereof interrupt theenergizing circuit for the holding winding IA of accelerating switch IA.Assuming that the motor starts upon closure of main switches IM and 2Mthe countervoltage in the motor circuit effects response of relay IVRand upon response of said relay the contacts lVR thereof interrupt theshunt circuit around the holding winding IA including resistance 1Holding winding 4A is thus subjected to the discharge of capacitor C andafter a predetermined prolonged period of delay the voltage in saidwinding is reduced to a value topermit response of accelerating switchEA under the action of its operating winding HA However, assuming thatthe load on the motor is such that the same fails to start immediatelyafter closure of main switches HM and 2M voltage relay iV'R remains incircuit closing position to provide for discharge of the energy inholding winding HA and capaci- 'tor C in a relatively short intervalthrough resistance R The holding effect of winding Al is thus quicklyreduced to permit operation of accelerating switch lA under the actionof its operating winding IA after a relatively short interval uponclosure of main switches EM and 2M. Response of accelerating switch IAexcludes resistance section R from the armature circuit of the motor.

Upon response of accelerating switch IA the contacts IA thereofinterrupt the energizing circuit for the holding winding 2A ofaccelerating switch 2A, and assuming'that the motor starts uponexclusion of resistance section B the counter-voltage in the motorcircuit effects response of voltage relay ZVR. Holding winding 2A isthen subjected to the discharge of capacitor C and after a prolongedperiod of delay the voltage in said holding winding is reduced to avalue to permit operation of accelerating switch 2A under the action ofits operating winding 2A However, if the load on the motor is such thatthe same fails to start upon exclusion of resistance section R voltagerelay ZVR remains in circuit closing position to provide for dischargeof the energy in holding winding 2A and capacitor C in a relativelyshort interval through resistance R Thus if the motor fails to startupon response of accelerating switch IA, accelerating switch 2A respondsafter a relatively short interval under the action of its operatingwinding 2A and the contacts 2A thereof shunt resistance section RImmediately upon response of accelerating switch 2A the contacts 2Ainterrupt the energizing circuit for the holding winding 3A ofaccelerating switch 3A. Assuming that the motor starts upon exclusion ofresistance section R the counter-voltage in the motor circuit effectsresponse of voltage relay 3VR. Holding winding 3A is then subjected tothe discharge of capacitor C and after a prolonged period of delay thevoltage in said holding winding is reduced to a value to permit responseof accelerating switch 3A. under the action of its operating winding 3AIf the load on the motor is such that the same fails to start uponexclusion of resistance section R voltage relay 3VR remains in closedposition to provide for discharge of the energy in holding winding 3Aand capacitor C in a relatively short interval through resistance 7 Thusif the motor fails to start upon response of accelerating switch 2A,accelerating switch 3A responds after a relatively short interval underthe action of its operating winding 3A 'and the contacts 3A thereofshunt resistance section R Upon response of accelerating switch 3A thecontacts 3A thereof open to disconnect the operating winding CT oftiming switch CT from lines L L Operating winding GT is then subjectedto the discharge of capacitor C and after a predetermined interval thevoltage of said winding is reduced to a value to permit opening of saidtiming relay. Upon opening of timing relay CT the contacts CT thereofclose prior to contacts CT and shunt the operating winding AS ofarmature shunt switch AS. Contacts A5 are thus opened to deenergize theoperating windings Ill/R ".iVR and 3VR of the voltage relays and toexclude resistance R. Also upon dropping out of timing relay CT thecontacts GT thereof connect the operating winding DB of dynamic brakingswitch DB across lines U, L through the medium of contacts 5M and 2M ofthe main switches IM and 2M.

Dynamic braking switch DB then responds to open its contacts DB andclose its contacts DB and DB Contacts DB in opening interrupt the shuntcircuit around armature A including resistance R Contacts DB in closingestablish an energizing circuit for the operating windings ofaccelerating switches 5A and 5A, said energizing circuit extending fromline L through contacts U'V of relay UV through contacts 2, 2 4 and 4 ofmaster switch MS to and through the operating windings 4A and 5A of saidaccelerating switches and through contacts iM and 2M of the mainswitches to line L Contacts DB in closing shunt the holding winding 4Aof accelerating switch 4A to permit response of said switch under theaction of its operating winding 4A Thus upon response of acceleratingswitch 4A, resistances R R and R are excluded from the motor circuit toeffect a further step-of acceleration of the motor.

Upon response of accelerating switch 4A the contacts 4A thereof shuntthe holding winding 5A to provide for response of accelerating switch 5Aunder the action of its operating winding 5A Upon response ofaccelerating switch 5A the contacts 5A thereof shunt acceleratingresistance section 1 Also upon response of accelcrating switch 5A thecontacts 5A thereof interrupt the energizing circuit for fieldaccelerating switch FA, and the operating winding PA! of said switch isthen subjected to the discharge of capacitor C to delay opening of saidswitch.

Aftera predeterminedinterval contacts FA open to connect resistances Rand R in parallel in the energizing circuit of shunt field winding F andthereafter contacts FA open to exclude resistance section R' from saidcircuit. Accelerating switch FA thus operates after a predeterminedperiod of delay upon response of accelerating switch 5A to provide twosteps of acceleration by weakening of the shunt field winding F Themotor may be stopped at any time during acceleration or after the sameis brought up to full running speed by momentary depression of either ofthe push buttons 5 or 6. Depression of either of said push buttonsinterrupts the afore-. described maintaining circuit for the operatingwinding UV of under voltage relay UV and said relay then drops out toopen its associated contacts UV and UV Upon opening of these contactsthe energizing circuits for operating coils of main switches lM and 2M,accelerating switches IA to 5A and dynamic braking switch DB are allinterrupted for return of said switches to normal position. Fieldaccelerating switch FA is then energized through the medium of contacts5A of accelerating switch 5A to provide for exclusion of resistancesections R and R. in the energizing circuit of shunt field winding F andresistance section R is connected across the terminals of armature A bycontacts DB of the dynamic braking switch DE. The -motor is thusdynamically braked to effect quick stopping thereof. As is apparent,upon dropping out of under voltage relay UV the master switch MS must bereturned to off position as a prerequisite to restarting of the motor.

In connection with the foregoing it should be noted that the abovedescribed controller is particularly adapted for use in connection withmotor driven-wire drawing machines and meets requirements hereinbeforediscussed. In other words, resistances R and R are proportioned toeffect starting of the driving motor under all load conditions, and uponstarting of the motor the controller insures slow speed operationthereof for 'a sufficient time to efiect the winding operationshereinbefore discussed. I

What we claim as new and desire to secure by Letters Patent is:

1. In a motor controller, in combination, a plurality of startingresistances in the motor circuit, aplurality'of electromagneticaccelerating switches each for shunting one of said resistassociatedwith said former means for timing the operation of said switches toeffect exclusion of said resistances from the motor circuit at a rapidrate until the ,motor starts and to thereafter efiect exclusion ofresistances remaining in the motor circuit at a reduced rate Q to bringthe motor up to running speed. I 3

2. In a motor controller, in combination, a plurality of startingresistances in the motor cir-' cuit, a plurality of electromagneticaccelerating switches'each for shunting one of said resistances,

each of said switches having an operating winding and a holding windingassociated therewith, means for controlling said windings to provide foroperation of said switches in a given sequence, and means associatedwith said holding windings for timing the operation of said switches toprovide for exclusion of said resistances from the motor circuit at arapid rate until the motor starts and to thereafter eifect exclusion ofresistances remaining in the motorcircuit at a reduced 1 rate to bringthe motor'up to running speed.

3. In a motor controller, in combination, a

plurality of electromagnetic accelerating switches each having acapacitor associated therewith for delaying operation thereof, controlmeans for effecting operation of said accelerating switches in a givensequence subject to delay by said capacitors, and means for modifyingthe delaying effect of said capacitors upon given electrical conditionsin the motor circuit.

4. In amotor controller, in combination, a plurality of electromagneticaccelerating switches each having a capacitor associated therewith for 4delaying operation thereof, control means for effecting operation ofsaid acceleratingswitches in a given sequence subject to delay by saidcapacitors and means subjected to control by the counter-voltage in themotor circuit for modifying the delaying efiect of said capacitors.

5. In a motor controller, in combination, a

plurality of electromagnetic accelerating switches each having acapacitor associated therewith for delaying operation thereof, controlmeans for ef- ,fecting operation of said accelerataing switcheswindings, means acting upon establishment of power connections for themotor to energize said operating windings and to successively interruptthe energizing circuits of .said holding'windings for successiveoperation of said switches, a capacitor associated with each of saidholding windings and coacting therewith upon interruption of itsassociated energizing circuit to delay operation of its associatedswitch, and means subjected tov control by the counter-voltage, of themotor for modifyingthe delaying efiect of said capacitors. I

7. In a motor controller, in combination, a plurality ofelectromagneticaccelerating switches each having a device associatedtherewith for delaying operation thereof, control means for effectingoperationof said accelerating switches in a ,given sequence subject todelay by their associated delaying devices, and means associated with atleast the first switch of said sequence for normally reducing thedelaying eflect of its associated delaying device, said latter meansbeing rendered ineffective upon starting of the motor.

8.'In a inotor controller, in combination; a

plurality of electromagnetic accelerating switches u each having adevice associated therewith for delaying operation thereof for apredetermined interval, control means for efiecting operation of 'sai daccelerating switches in a given sequence plurality of startingresistances in the motor cir:

W for successive operation of said switches, a device associated witheach of said holding windings and coacting therewith upon interruptionof associated energizing circuit to delay operation of its associatedswitch, means associated in L certain of said devices for normallyreducing the '5 delaying efiect'thereof, said latter means beingrendered inefiective upon starting of the inoton PAISLEY B. HARl/VOQD. IJOE-m M, NEWBEAN. ll

